Abstract: A system for monitoring the temperature of a patient undergoing an examination in strong magnetic field, such as that created by an MRI machine. The system includes a temperature sensor composed of a high accuracy temperature probe that is coupled to an electronics module by an RF current reduction network. The temperature sensor is excited by a constant current provided on two of the four leads comprising the RF current reduction network. The remaining two leads connect to an instrumentation amplifier. All of the circuitry is located within a Faraday housing, and all connections made between the sensor and the electronics module pass through RF filters mounted in the Faraday housing, allowing the electronics module to be positioned within the strong magnetic field.

Abstract: A system for monitoring an ECG during a patient examination in a strong magnetic field, such as that created by an MRI machine, which eliminates motion artifacts affecting the accurate reading of the ECG. The system modulates the strong magnetic field and then generates an error correction signal substantially equal to the motion artifact signal in timed relationship with the modulated signal that is subtracted from the measured ECG signal to produce a more accurate ECG signal.

Abstract: A system for monitoring an ECG during an MRI examination which permits the monitoring system to be located near the patient and which eliminates artifacts affecting the accurate reading of the ECG. The system allows for control of lead select and battery on stand by mode and can monitor battery state and lead off conditions.

Abstract: An inductive level sensor has inductively coupled primary and secondary windings. Circuitry drives the primary with an AC signal of constant current magnitude and selected frequency f to induce in the secondary, a voltage signal V of magnitude .vertline.V.vertline., frequency f and phase difference .phi. from the driving signal. Circuitry operates to generate a voltage output signal proportional to .vertline.V.vertline. cos (.phi.-.theta.), where .theta. is a selectively set phase shift factor. By properly and selectively adjusting the frequency f and phase shift factor .theta., an output signal .vertline.V.vertline. cos (.phi.-.theta.) can be provided which self-compensates for changes in mutual inductance caused by operating temperature variations so that an output signal is produced which is substantially linearly proportional to changes in the level of a pool of liquid metal being monitored. Disclosed also is calibration circuitry and circuitry for converting the voltage signal .vertline.V.vertline.